This invention relates to a radio communication apparatus for selectively receiving a plurality of call signals indicative of a plurality of call numbers, respectively. The radio communication apparatus may be a radio paging receiver, a transceiver, or the like although description will be mainly made about the radio paging receiver.
A radio paging receiver of the type described deals with a plurality of call signals and a plurality of message signals following the call signals, respectively. The radio paging receiver has an individual call number and comprises a receiving circuit for receiving each of the call signals as a received call signal.
In a conventional radio paging receiver, a control unit is connected to the receiving circuit. The control unit has a judging function for judging whether or not the received call signal is coincident with the individual call number. When the received call signal is coincident with the individual call number, the control unit controls an annunciator, such as a tone generator or a vibrator, to make the annunciator carry out an announcing operation. For example, if the annunciator the tone generator, the annunciator generates a particular audible tone to announce reception of the received call signal which is coincident with the individual call number.
When the received call signal is coincident with the individual call number, the control unit receives the message signal following the received call signal as a received message signal representative of a message. The control unit comprises a memory and stores the message in the memory as a stored message. Simultaneously, the control unit supplies the message signal to a display unit, such as a liquid crystal display provided with a back light. The display unit puts the back light on and displays the message. In the manner which is presently being described, the stored message is arbitrarily read out of the memory and can be displayed by the display unit.
The radio paging receiver further comprises a push button switch which is manually operable to set an operation mode of the annunciator, the display unit., or the like. Briefly, if the push switch is pushed by the possessor on generation of the particular audible tone, the control unit controls the annunciator to make the annunciator stop the announcing operation. After stopping of the announcing operation, if the push button switch is pushed again, the control unit controls the display unit to make the display unit put the back light off and stop display of the message. After this the radio paging receiver is put into a standby mode. In the standby mode, if the push button switch is pushed, the control unit reads the stored message out of the memory and supplies the stored message to the display unit. In this state, the display unit puts the back light on again and displays the stored message. Thus, the stored message can arbitrarily be displayed by the display unit.
A recent remarkable development of an integrated circuit technique has rendered the radio paging receiver compact or portable and multifunctional. Preferably, the radio paging receiver has a long life. Inasmuch as a battery is used as a power source in the radio paging receiver, the radio paging receiver has a life time dependent upon the life of the battery. Therefore, electric power must not be wasted in the radio paging receiver. In other words, useless and unintentional operation should be prevented.
The radio paging receiver comprises a case which contains a circuit board having circuit arrangements of the radio paging receiver. The push button switch is fixed to the circuit board so that the push button switch protrudes from a main surface of the case. This causes a disadvantage for the following reason. The radio paging receiver is often put in a pocket, such as a breast pocket of a jacket, of a possessor together with a small notebook or the like. The radio paging receiver may be put in a bag, such as an attache case, together with books or the like. In this case, the small notebook or the books may push the push button switch regardless of possessor's intention. In this time, if the radio paving receiver is put into the standby mode, the display unit puts the back light on and is put into display operation of the stored message regardless of whether the possessor wants it or not. Such a display operation is, so to speak, an unintentional display operation. This means that the electric power is wasted in the radio paging receiver, particularly by unintentionally activating the back light and stored message display operation.